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Matt Godbolt sold me on Rust by showing me C++

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611 points LorenDB | 10 comments | 06 May 25 17:51 UTC | HN request time: 0.841s | source | bottom
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dvratil ◴[06 May 25 18:20 UTC] No.43908097[source]▶
The one thing that sold me on Rust (going from C++) was that there is a single way errors are propagated: the Result type. No need to bother with exceptions, functions returning bool, functions returning 0 on success, functions returning 0 on error, functions returning -1 on error, functions returning negative errno on error, functions taking optional pointer to bool to indicate error (optionally), functions taking reference to std::error_code to set an error (and having an overload with the same name that throws an exception on error if you forget to pass the std::error_code)...I understand there's 30 years of history, but it still is annoying, that even the standard library is not consistent (or striving for consistency).

Then you top it on with `?` shortcut and the functional interface of Result and suddenly error handling becomes fun and easy to deal with, rather than just "return false" with a "TODO: figure out error handling".

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90s_dev ◴[06 May 25 19:03 UTC] No.43908540[source]▶
I like so much about Rust.

But I hear compiling is too slow.

Is it a serious problem in practice?

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1. Seattle3503 ◴[06 May 25 19:15 UTC] No.43908634[source]▶
Absolutely, the compile times are the biggest drawback IMO. Everywhere I've been that built large systems in Rust eventually ends up spending a good amount of dev time trying to get CI/CD pipeline times to something sane.

Besides developer productivity it can be an issue when you need a critical fix to go out quickly and your pipelines take 60+ minutes.

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2. ◴[06 May 25 19:25 UTC] No.43908723[source]▶
3. lilyball ◴[06 May 25 19:29 UTC] No.43908757[source]▶
Don't use a single monolithic crate. Break your project up into multiple crates. Not only does this help with compile time (the individual crate compiles can be parallelized), it also tends to help with API design as well.
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4. mixmastamyk ◴[06 May 25 19:55 UTC] No.43908980[source]▶
It compiles different files separately, right?

With some exceptions for core data structures, it seems that if you only modified a few files in a large project the total compilation time would be quick no matter how slow the compiler was.

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5. Seattle3503 ◴[06 May 25 20:05 UTC] No.43909085[source]▶
Every project I've worked on used a workspace with many crates. Generally that only gets you so far on large projects.
6. conradludgate ◴[06 May 25 20:09 UTC] No.43909112{3}[source]▶
Sorta. The "compilation unit" is a single crate, but rustc is now also parallel, and LLVM can also be configured to run in parallel IIRC.

Rust compile times have been improving over time as the compiler gets incrementally rewritten and optimised.

7. nicoburns ◴[06 May 25 22:04 UTC] No.43910113[source]▶
If you have the money to throw at it, you can get a long way optimising CI pipelines just by throwing faster hardware at it. The sort of server you could rent for ~$150/month might easily be ~5x faster than your typical Github Actions hosted runner.
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8. Seattle3503 ◴[06 May 25 23:33 UTC] No.43910741[source]▶
Yes, this is often the best "low-hanging fruit" option, but it can get expensive. It depends how you value your developer time.
9. sethammons ◴[07 May 25 09:13 UTC] No.43913607[source]▶
We have 60 minutes deploy pipelines and are in python. Just mentioning that since, in theory, we are not penalized for long compile times.

Fast ability to quickly test and get feedback is mana from the gods in software development. Organizations should keep it right below customer satisfaction and growth as a driving metric.

10. hobofan ◴[07 May 25 11:23 UTC] No.43914316[source]▶
Besides faster hardware, one of the main features (and drawbacks) you get with self-hosted runners is the option to break through build isolation, and have performant caches between builds.

With many other build systems I'd be hesitant to do that, but since Cargo is very good about what to rebuild for incremental builds, keeping the cache around is a huge speed boost.